This invention relates to a roll-type insect screen assembly for covering a window or door opening in an insect-proof and air-permeable manner. The assembly comprises a flexible, preferably netlike insect screen which is guided in lateral guide rails mounted on the outside of the opening and which is adapted to be wound onto a roller. The roller is rotatably supported above the opening and is rotatable by means of an actuating device and adapted to be locked in a given rotary position. The assembly includes a weight bar at the lower end of the insect screen, with the weight bar having sufficient weight to cause the insect screen to automatically unwind upon release of the roller.
Various kinds of roll-type insect screen assemblies in the form of automatic blinds are known. As far as automatic blinds are concerned, the roller is connected to a torsion spring which is stretched when the insect screen is unwound, so that the insect screen can be wound up by resilient force. Automatic blinds have the disadvantage that they must be secured in the unwound position. This can be effected by means of a bar which is secured to the lower end of the insect screen and is snapped into a holding device mounted on the window sill. Prior to the rewinding of such insect screen, the screen must be unlocked, which is troublesome and might even be dangerous when performed by children or elderly people who have to lean out of the window for this purpose. Another disadvantage of automatic blinds is that the resilient force of the torsion spring diminishes after a relatively short service life, so that the unwound insect screen can no longer be stretched to a sufficient degree to ensure perfect covering of a window or door opening. Also, the automatic restoring effect is impaired. Furthermore, it is difficult to secure the bar mounted on the lower end of the insect screen to the window sill or door threshold in such a way that an insect-proof covering is ensured.
Roll-type insect screen assemblies are also known wherein the insect screen is pulled upwards and rolled up by hand by means of a pull strap or a pull cord which is unwound from a pull roll connected to the roller and possibly wound onto a counter-roll. The insect screen is made of thin, light weight gauze, is mounted in lateral guides for an insect-proof covering of the building opening. A pull cord, attached to the lower bar of the screen, is manually pulled to unwind the screen from the roller. Hence, it is also troublesome to handle roll screen assemblies of this type. Another disadvantage of such a roll-type insect screen assembly, which can be wound in the manner of a roller shutter, is that the screen is hardly stretched in the unwound state because of its light weight, so that special precautions have to be taken to prevent the thin gauze from being torn out of the lateral guide rails because of wind gusts. Despite all of these efforts, the gauze which is minimally stretched in the longitudinal direction of the insect screen will flap in a breeze, which is undesirable and impairs the service life of the gauze.
DE-OS 28 39 490 and DE-GM 18 20 012 disclose roll-type insect screen assemblies in which the lower end of the screen curtain roll is connected to a bar. The bar has sufficient weight to automatically pull the gauze curtain downward when the associated roll is unlocked. The weight bar is made from wood or metal, requiring a great cross-sectional dimension, to have sufficient weight. These screen assemblies, however, cannot be used in combination with an existing roller shutter because the lateral guide rails of the insect screen have to be arranged between the shutter and the window. The already known roll-type insect screen assemblies cannot be accommodated in this limited space. Moreover, insects may enter into the grooves of the guide rails and hence into the interior of the building.
US-PS 25 48 040 discloses an insect blind for windows having a lower bar on which guide pins of a considerable thickness are arranged and project beyond a plastic film which is provided as a cover. The exclusion of insects around the sides is also not possible with this configuration.
Although DE-GM 85 05 858 shows the possibility of mounting a lower flat section on a screen curtain, the necessary weight is insufficient for unwinding the antifly curtain automatically.
DE-GM 18 64 087 discloses a deformable cover strip as a lower end of an insect-screen roller shutter, the cover strip being adapted to be put on a window sill. This configuration has the disadvantage that the strip cannot adapt to irregularities of the contact surface to prevent entry of insects.
DE 39 36 343 C2 of A. Wildt, for which an application was filed Nov. 2, 1989, describes a roll-type insect screen assembly which ensures a virtually fully insect-proof covering of a window or door opening, the insect screen assembly being adapted to be combined with an already existing roller shutter.
In accordance with the above publication, the weight bar at the bottom of the screen consists entirely or partly of lead, and the weight thereof is at least 1 kg/m. With such a weight it is possible to overcome all sliding frictional forces between the screen edges and the lateral guide rails, so that the insect screen unwinds automatically and in an entirely smooth way. Also, the screen is held in such a taut state during the unwinding operation that the frictional forces acting from the guide rails onto the lateral edge portions are minimized. As a result of the vigorously stretched state of the insect screen, even great wind forces cannot make the lateral edge portions detach from the guide rails. Flapping of the netlike gauze is prevented.
Moreover, the weight of the bar ensures that the insect screen will be tightly wound onto the associated screen reel or roller, resulting in a compact coil of a very small diameter. It is, therefore, possible to accommodate the screen roller assembly in an existing roller shutter casing because the small space required by the assembly and operation of the device.
As a result of the material employed in the bar, the necessary weight can be achieved with a bar having only a height of about 25 mm at a width of 10 mm. It is thus possible to install the roll-type insect screen assembly in addition to an already existing roller shutter because the weight bar can be accommodated in a very small space between the roller shutter and the window or between the guide rails of the roller shutter and the architecture of the window or door.
Preferably, the lower end of the insect screen is mounted on a guide rail which is accommodated in a groove of the weight bar and projects at both sides, the weight bar being slightly shorter than the clearance between the lateral guide rails. The weight bar transmits its weight via the guide rail to the screen over the whole width thereof, in order to fully stretch the edges.
To provide additional protection against insects, an elastically deformable bristle strip is provided on the window sill or other opening and is engaged by the weight bar when the screen is closed. The bristle strip adapts to all uneven spots because of the very great number of deformable bristles, and a perfect seal against insets is ensured. Since the bristles can be bent easily and are resilient, even irregular recesses in a contact area are sealed against the entry of insects. The high weight of the bar insures that the screen will remain taught while providing a seal with the strip.